How to Fast With Protein Shakes for Weight Loss

Protein shakes are a popular way to help lose weight.
Image Credit: Yulia Lisitsa/iStock/GettyImages

Using a protein shake fast is becoming a popular way to drop weight quickly, but is it a healthy and safe way to get the job done? Protein shakes often lack complete nutrition, so long-term use may lead to deficiencies.



According to the Centers for Disease Control and Prevention National Center for Health Statistics, in 2013 to 2016, nearly half of American adults "tried to lose weight in the last 12 months." Data from Research and Markets indicates that as of 2018, the weight loss industry was worth a record $72 billion.

What's a Protein Shake Fast?

This weight loss approach involves consuming nothing but protein shakes for a predetermined amount of time. Some fasts recommend one day, while others suggest five days to a week. The idea is that by limiting your calorie intake but supplying your body with the protein it needs, you'll be able to see potentially substantial weight loss by the end of the fast.


Video of the Day

Chances are you'll see weight loss, but the reality is that you aren't likely to be able to sustain it. Your body requires fat, protein and carbohydrates, along with other nutrients to operate at its best, and cutting macronutrients isn't a healthy approach over the long-term.

It's a better idea to focus on making healthy lifestyle choices over time rather than looking for a quick solution. You didn't put the weight on overnight, so it's unreasonable to think you should be able to drop it that fast.


If you choose to use a protein shake fast to reach your weight loss goals, check with your healthcare professional for approval before you begin, to ensure you're fasting safely.

Read more: You Are When You Eat? How Intermittent Fasting Affects Weight Loss

Use High-Quality Protein Shakes

Not all protein shakes are created equal. Many of them are high in sugar or artificial sweeteners, which can defeat the purpose of using a fast. For more control over your protein intake, you may want to consider fasting with protein powder. This allows you to mix the drinks on your own and will save you money compared to buying a ready-to-drink shake.


For the highest quality, consider fasting with whey protein. Though more expensive, grass-fed whey proteins are a better alternative much like the same way grass-fed meat is better for you because the cow's diet affects their milk. If you can't opt for grass fed, look for a protein powder with the fewest ingredients possible.

According to Harvard Health Publishing, the USDA-recommended dietary allowance of protein is 0.36 grams of good quality protein per pound of body weight or 0.8 grams of protein per kilogram. Simply multiply your weight in pounds by 0.36 to figure out your daily recommended intake. For a sedentary woman who weighs 150 pounds, that amounts to 54 grams per day. If you're working out, you will need to consume more protein, as this does not factor age, physique, or activity level.



According to a scientific review of multiple studies, published in April 2015 in the American Journal of Clinical Nutrition, higher protein diets that contain between 1.2 and 1.6 grams of protein per kilogram of body weight and potentially include meal-specific protein quantities of at least 25 to 30 grams per meal assist with improved appetite, satiety, weight loss and fat mass loss.

The lack of compliance with the prescribed higher protein diets outside the study environment is what makes it difficult to confirm a sustained effect of protein over the long term.


Read more: Why Trying a Water Fast Is So Risky

Keep It Short

A protein shake isn't the same as a meal replacement shake. While meal replacements aim to closely resemble a nutritionally complete meal, protein shakes generally don't contain other nutrients. If you use a protein shake diet too long, you're setting yourself up for nutrient deficiencies. If you can fast one day a week, that should allow you to lose weight without succumbing to nutrient deficiencies.




Report an Issue

screenshot of the current page

Screenshot loading...